1. Field of the Invention
The present invention relates to an optical pickup device for use in recording/reproducing on an optical recording medium, such as a CD (Compact Disk), a DVD (digital Versatile Disk), a Blu-ray Disk (registered trademark), and, more particularly, to an adhesive fixing technique for a laser diode or a photodetector, etc.
2. Description of the Related Art
There are some types of optical systems as an optical pickup device for use in recording/reproducing on an optical recording medium (CD, DVD) and an optical disk drive device in which the optical pickup device is embedded. As illustrated in FIG. 13, one optical system leads output light from a light emitter 93 (laser diode (hereinafter referred to as an LD)) to an object lens through any of a lens 95, a prism 96, and a mirror 98, and converges the light onto an optical disk. Another optical system causes light reflected from the optical disk to be focused on a photodetector 94 through an object lens, a reflection mirror, a prism, and a lens 97. In these devices, the LD 93 and the photodetector 94 need to be fixed in an optically appropriately adjusted position with respect to a case 90 of the optical pickup device. Thus, generally, in the structure, the optical device (LD and photodetector 94) is once adhered to a holder 99 having a form suitable for adhering to the case. After the holder 99 and the case 90 are adjusted into an optically appropriate position, they are fixed in an appropriately three-dimensional position with the thickness of the adhesive agent layer, using a ultraviolet (UV) cure adhesive agent.
Variations of application positions, forms, and areas of the adhesive agent cause a variation in the adhesive strengths. In recent years, in some type of device, the case for installing the optical parts is made from a resin. This type of device is increasing. The resin case has a lower adhesive strength with the installed parts, than the adhesive strength of a metal case, and is likely to be separated at the interface. Thus, it is desired to improve the adhesive strength. Further, when an increased amount of adhesive agent is applied for the purpose of improving the adhesive agent, conventionally, a problem is that the adhesive agent may undesirably block the optical path.
Patent documents 1 and 2 are provided to disclose an optical pickup device, as prior art documents.